<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>id选择器</title>
    <style>
        #red{
            color: red;
            font-size: 20px;
        }
        #blue{
            color: blue;
            font-size: 50px;
        }
    </style>
</head>
<body>
    <p id="red">id选择器</p>
    <p id="blue">id选择器</p>
</body>
</html>